{"id":2258,"date":"2017-06-20T13:38:20","date_gmt":"2017-06-20T18:38:20","guid":{"rendered":"http:\/\/pugix.com\/synth\/?p=2258"},"modified":"2023-02-15T13:42:08","modified_gmt":"2023-02-15T18:42:08","slug":"esoterica-spike-ring","status":"publish","type":"post","link":"https:\/\/pugix.com\/synth\/esoterica-spike-ring\/","title":{"rendered":"Esoterica Spike Ring"},"content":{"rendered":"

\"\"<\/a>Peter Blasser’s paper circuits are made by printing out a graphic, such as the above, at the right scale to match up with the physical sizes of the actual components, resistors, capacitors, integrated circuits, etc..  The printout is glued to a piece of stiff cardboard, then holes made with a needle, the components inserted and connected by wiring on the back side.  Peter’s graphics are laid out in a planar manner, such that most of the wiring can be done without crossing wires.<\/p>\n

Some people make printed circuit boards based on paper circuits.  I bought one for the Esoterica Spike Ring from Dennis Verschoor<\/a> that he had assembled The Spike Ring consists of a filter circuit combined with a pulse generator.<\/p>\n

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It has four pots. Pitch and Resonance apply to the filter, Delay and Chaos to the pulse generator. There is a designated audio output (filter band pass), filter high and low-pass outputs, and a pulses output. There is also a balanced input indicated by a castle symbol, for FM of the filter, that I tried hooking to a piezo disk with some success.  The swirly symbol node is an input for affecting chaos. The antenna-like symbol node is an input that seems intended to gate the pulses into the filter.  Here’s the full schematic.<\/p>\n

\"\"<\/a>The top portion of the schematic shows a state-variable filter topology, with the input ‘P’ coming out of the pulse generator circuit below.  The band pass output is AC-coupled, while the high and low pass outputs have 10K series resistors going to nodes.  Note that X and Y resistors are 10K and CHAO is 220K.  I made one circuit change, to lower the resistor from the Delay pot from 1M to 470K so that the pot would have an effect.  The castle symbol indicates a dual input that is clearly intended for FM, but we’re not sure what the intended use of it is.<\/p>\n

I don’t understand the chaos pulse generator very well.  A scope shows high frequency small oscillations on pins 2 and 3 of the TL074 chip.  These produce a continuous and noisy pulse on pin 1, but this signal doesn’t get through to the filter until a finger (or some other signal) is placed on the node with the antenna symbol.  Then, the pulses are passed to the filter and also to the star symbol pulses out node.<\/p>\n

We made a video of me fooling around with it.  Thanks, Diana, for the video processing!<\/p>\n